This invention relates to oral, settable, dental compositions prepared by interacting a metallic base with a high molecular weight polycarboxylic acid in the presence of a reaction rate activator and a hydrocarbon binding resin.
Typically, settable dental compositions are used for taking dental impressions and, in addition, are used as pulp capping materials and as temporary cements. A settable composition is one which, after being formed, sets into a solid, cementitious, coherent mass.
In order for a settable composition to have practical utility in the dental field, it must set to a cohesive mass, following admixture of the components, within a relatively short period of time, usually not longer than about 15 minutes. Since the rate of set in the reaction of a metallic base with a high molecular weight polycarboxylic acid is too slow for dental purposes,it is necessary to include in the formulation a reaction rate activator, sometimes referred to as an accelerator, in order to increase the rate of reaction and to reduce the set time.
In addition, it has been customary in the art to include a carboxylic acid binding resin in the formulation to improve adhesiveness, impart toughness and reduce brittleness of the interacted product.
Canadian Pat. No. 700,633 (corresponding to U.S. Pat. No. 3,028,247-Molnar, 1962) discloses the use of (a) carboxylic acid resins such as modified resin and (b) reaction rate accelerators exemplified by azelaic acid, ethanol and zinc acetate in the preparation of settable dental compositions based on the interaction of a monocarboxylic fatty acid having a melting point below 65.degree. C. with a polyvalent metallic base. The patentee emphasizes that the resin employed must possess unreacted or available carboxyl groups.
U.S. Pat. No. 3,837,865 (Pellico, 1974) discloses the preparation of settable dental compositions by interacting a polycarboxylic acid such as C.sub.36 dimer acid with a metallic base in the presence of a carboxylic acid resin such as modified rosin and a reaction rate activator exemplified by acetic acid and zinc acetate.